1. Field of the Invention
The present invention relates to a sealing member for a fluid valve exemplified by, but not limited to, a water tap or a ballcock float valve, and to a valve closure member incorporating the sealing member for sealing a fluid valve.
2. Description of the Related Art
A conventional domestic water tap consists of a tap head threadingly connected to a tap body, the tap body including a water passageway having a fluid inlet, a fluid outlet, and a tap seat therebetween. A spindle provided with a handle at one end is threadingly retained within the head so that rotation of the spindle in opposite directions moves the spindle up and down (i.e., linearly) within the tap body. A washer assembly is typically received within a hole formed in an opposite end of the spindle and is arranged for seating on the tap seat. Thus, as the spindle is turned in opposite directions, the washer assembly can be moved up and down (i.e., linearly) into and out of contact with the tap seat to effect opening and closing of the tap. To this end, the washer assembly typically includes a resilient sealing member which is forced against the tap seat by the linear motion of the spindle to effect the closing of the tap.
This type of washer assembly and sealing member suffer from various problems. Because the sealing member is often pushed up hard against the seat it tears, splits or otherwise fractures and thus requires frequent replacement in order to prevent leakage from the tap. Further, the washer assembly provides a very rigid shut off of water flow and leads the production of water hammer.
The HYDROSEAL.TM. washer was invented with a view to overcoming the above problems. The HYDROSEAL washer is designed to retrofit to any conventional water tap in place of the normal washer assembly described above. The HYDROSEAL washer as described in Australian Patent Number 567174, consists of a stem formed together with a disc, the stem adapted to removably located within a bore of a conventional tap spindle. The disc has a circular-shaped recess in which a circular shaped plate is fixed. The circular plate is spaced from the walls of the recess so as to define an annular recess and circular channel in fluid communication with each other. The circular channel is trapezium shaped in cross section and configured to house an o-ring seal which protrudes from the disc and plate. The o-ring seal is designed to seat upon a tap seat on closure of the tap. The plate includes an aperture which allows water to flow into the annular recess and circular channel and thus force the a-ring seal against the tap seat. Thus, closure of the tap is assisted by water pressure.
While the HYDROSEAL washer functions adequately, it is reasonably complex in construction and therefore expensive. Further, the o-ring seal is relatively rigid and does not effectively seat upon uneven or rough tap seats.
Another type of valve, known as the ballcock float valve, is used to regulate the flow of mains water to a lavatory cistern. The ballcock valve includes a tube which is located within the cistern into which water entering the cistern flows. The tube at one end has a water outlet against which a plunger seats so as to open or close the flow of water to the cistern. The plunger includes a sealing washer which seats around a periphery of the water outlet. The ballcock float valve further includes a fulcrum member having a float connected at one end, the fulcrum member adapted at the other end to bear against the plunger so as to seat and unseat it from the water outlet. Frequent seating against the water outlet progressively wears and or deforms the sealing washer. When in this condition, the washer cannot completely seal against the water outlet and mains water slowly leaks into the cistern. This water then overflows into the toilet proper and is as wasted. Additionally, when the plunger is seated it compresses the washer which increases the volume of water held in the cistern for flushing, again leading to the wasting of water. To avoid this, the plunger or other components of the ballcock float valve require servicing or replacement.